Rewrite External Changes dialog to use the Merge Entries dialog

[koppor]

When a bibtex file is modified externally, JabRef shows it at the left side:

After clicking "Review changes", following dialog pops up:

To be consistent with the other JabRef dialogs, it should render as follows:

See https://help.jabref.org/en/MergeEntries

If possible, rewrite in JavaFX.

[Siedlerchr]

Only works for entries and not for metadata!

[koppor]

Sure. I asusme that mostly BibTeX entries are changed externally. The Merge Entries Dialog is more intuitive than the old one.

Metadata is serialised as follows:

@Comment{jabref-meta: keypattern_techreport:[authorsAlpha][year]-TR;}

Thus, the overall concept is

@Comment{jabref-meta: KEY:VALUE}

So, the merge entries dialog can be reused to list all KEYs as field and all VALUEs as values of the fields.

[koppor]

The latest JabRef is "good enough"

Howver, in the context of the meta data, we show barly anything what's changed: